Answer:
(a) The magnetic energy density in the field is 6.366 J/m³
(b) The energy stored in the magnetic field within the solenoid is 5 kJ
Step-by-step explanation:
magnitude of magnetic field inside solenoid, B = 4 T
inner diameter of solenoid, d = 6.2 cm
inner radius of the solenoid, r = 3.1 cm = 0.031 m
length of solenoid, L = 26 cm = 0.26 m
(a) The magnetic energy density in the field is given by;
![u _B = (B^2)/(2\mu_o) \\\\u _B = ((4)^2)/(2(4\pi*10^(-7)))\\\\u_B = 6.366*10^6 \ J/m^3](https://img.qammunity.org/2021/formulas/physics/college/jb0ni8plyuk5a4i21tvspwokw84f8in1tp.png)
(b) The energy stored in the magnetic field within the solenoid
![U_B = u_B V\\\\U_B = u_B AL](https://img.qammunity.org/2021/formulas/physics/college/zx9o01w1tqy5wdeg0ab61vxy56vhcbk8k6.png)
![U_B = u_B(A)(L)\\\\U_B = 6.366*10^6(\pi * 0.031^2)(0.26) \\\\U_B = 4997.69 J\\\\U_B = 5 \ KJ\\](https://img.qammunity.org/2021/formulas/physics/college/veo3bas3f43ldgg9hlprlei68sfv1omn8s.png)